Preservation of biopharmaceutical materials, such as cryopreservation, is important in the manufacture, use, transport, storage and sale of such materials. For example, biopharmaceutical materials are often preserved by freezing between processing steps and during storage. Similarly, biopharmaceutical materials are often frozen and thawed as part of the development process to enhance the quality or to simplify the development process.
When freezing biopharmaceutical materials, the overall quality, and in particular pharmaceutical activity, of the biopharmaceutical materials is desirably preserved, without substantial degradation of the biopharmaceutical materials.
Currently, preservation of biopharmaceutical material, particularly in bulk quantities, often involves placing a container containing liquid biopharmaceutical material in a cabinet freezer, chest freezer or walk-in freezer and allowing the biopharmaceutical material to freeze. Specifically, the container, which is typically one or more liters in volume and may range up to ten or more liters, is often placed on a shelf in the cabinet freezer, chest freezer or walk-in freezer and the biopharmaceutical material is allowed to freeze. These containers may be stainless-steel vessels, plastic bottles or carboys, or plastic bags. They are typically filled with a specified volume to allow for freezing and expansion and then transferred into the freezers at temperatures typically ranging from negative 20 degrees Celsius to negative 70 degrees Celsius or below.
To ensure efficient use of available space inside the freezer, containers are placed alongside one another and sometimes are stacked into an array with varied spatial regularity. Under these conditions, cooling of the biopharmaceutical solution occurs at different rates depending on the exposure of each container to the surrounding cold air, and the extent to which that container is shielded by neighboring containers. For example, containers placed close to the cooling source or those on the outside of an array of containers would be cooled more rapidly than those further away from the cooling source and/or situated at the interior of the array.
In general, adjacent placement of multiple containers in a freezer creates thermal gradients from container to container. The freezing rate and product quality then depend on the actual freezer load, space between the containers, and air movement in the freezer. This results in a different thermal history for the contents of the containers depending on their location in a freezer, for example. Also, the use of different containers for individual portions of a single batch of biopharmaceutical material may cause different results for portions of the same batch due to different thermal histories resulting from freezing in a multiple container freezer, particularly if the storage arrangement is haphazard and random. Another consequence of obtaining a range of freezing times is that certain containers may freeze so slowly that the target solute can no longer be captured within the ice phase, but remains in a progressively smaller liquid phase. This phenomenon is referred to as cyroconcentration. In some cases such cyroconcentration could result in precipitation of the biopharmaceutical product, thus resulting in product loss.
Disposable bulk storage containers such as plastic bags or other flexible containers often are damaged, leading to loss of the biopharmaceutical material. Particularly, the volumetric expansion of the biopharmaceutical materials during freezing could generate excessive pressure in an over filled bag or in a pocket of occluded liquid adjoining the bag material, possibly leading to rupture or damage to the integrity of the bag. Moreover, handling of such disposable containers, such as plastic bags, during freezing, thawing, or transportation of these containers often result in damage thereof, due, for example, to shock, abrasion, impact, or other mishandling events arising from operator errors or inadequate protection of the bags in use.
Similarly, thawing of bulk biopharmaceutical materials typically involved removing them from a freezer and allowing them to thaw at room temperature. Such uncontrolled thawing can also lead to product loss. Generally, rapid thawing of biopharmaceutical materials results in less product loss than slower thawing. Further, it may also be desirable to control temperature of the biopharmaceutical materials during a thawing process since exposure of some biopharmaceutical materials to elevated temperatures may also lead to product loss. For example, it may be desirable to maintain a thawing biopharmaceutical material at about 0° C. when still in liquid and solid form during thawing thereof.
Further, it may be desirable to mix liquid bulk biopharmaceutical material at a homogeneous temperature above, below, or at an ambient temperature level. The mixing of biopharmaceutical materials in containers is important in the manufacture, use, transport, and storage of such materials. For example, biopharmaceutical materials are often blended, compounded, or formulated by mixing during processing steps and kept homogeneous during storage. Similarly, biopharmaceutical materials are often blended, compounded, or formulated by mixing as part of this development process to enhance the quality or to simplify the development process.
Currently, in some aspects, mixing of bulk biopharmaceutical materials involves transferring the product out of a container comprising the biopharmaceutical materials into a tank with a mechanical agitator, mixing and transferring the material back to the container. During those operations the containment may be broken and the product sterility and purity compromised. The homogeneous product may separate again after transfer back to its original container. Multiple transfers may expose product to excessive shear and to gas-liquid interfaces, which may adversely affect the product. Thus, it is preferable if such mixing can be accomplished without transferring the biopharmaceutical material out of the container or inserting a mixer into the container, i.e., noninvasive mixing is preferred. When utilizing such noninvasive mixing, the overall quality, sterility, and in particular pharmaceutical activity, of the biopharmaceutical materials is desirably preserved, without substantial degradation of the biopharmaceutical materials.
Thus, there is a need for systems and methods for freezing, thawing and mixing biopharmaceutical materials, particularly in bulk quantities, that are controlled, do not result in loss of biopharmaceutical material, and are repeatable.